@Martin Timothy,
Right you are.... and It's particularly significant when it comes to WTC7, which wasn't even hit by a plane. It's really pretty worthless to bother with science in this forum though, these guys don't seem interested in solutions or getting to the bottom of anything, it seems to be more about agitation, distraction and fabrication.
Though the possible composition and placement of the explosives can be endlessly debated, but the fact that they were indeed composed and placed cannot....
The conditions required for gravitational acceleration to occur have been known for centuries - "
The condition under which a body is, literally, free to fall under the influence of the local gravitational field with no resistance to its acceleration."....
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....and the
progressive collapse of the building (starting with column 79 on the left)....
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....that essentially happens
all at once....
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....is
clearly inconsistent with what we
empirically know of natural progressive structural failure (defined as a time consuming process of individual/sequential/simultaneous failures involving a number of related structural components).
It's a matter of
empirical fact that, even if a giant laser beam were to suddenly vaporize all but the North Face of the building, resulting in the remaining exterior columns immediately beginning to buckle all at once, free fall still would not occur.
The strength of buckled columns, whether one or a thousand, whether one at a time or all at once (or any combination thereof) won't just go from 100% to 0%
when they buckle, they'll go from 100% to 0%
while they buckle and that takes
time.
The mechanism of buckling (a mode of natural progressive structural failure), whether caused by heat....
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[center]Control on the right, details....
http://picasion.com/pic76/ef2992a1bed34a1ad9d2e8f520c5ad7e.gif[/center]
....or by overloading....
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[center]Control on the right, details....
http://picasion.com/pic76/ef2992a1bed34a1ad9d2e8f520c5ad7e.gif[/center]
....
absolutely cannot create the conditions required for gravitational acceleration to occur, it's literally impossible. Some force
must be introduced to quickly remove
all support from beneath the
literally falling visible upper part of the building seen in the video....
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It's a
physical impossibility for the lower part of the asymmetrically damaged building (reportedly three core columns and nine perimeter columns) to have naturally progressively collapsed in
any way that could result in the upper part of the building symmetrically descending straight down through itself at gravitational acceleration (NIST probable collapse sequence starting with column 79 circled below) for
any period of time....
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....and there is
absolutely no mode or combination of modes of natural progressive structural failure driven
solely by gravity that can
ever give rise to the conditions required (below) for free fall to have occurred at
any point during it's descent....
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The scenario (below) is an
absolute physical impossibility....
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There is simply no point during a natural progressive gravity driven collapse of a steel frame skyscraper like this where one could say....
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"Hold it.... right there! That's the point where all the steel columns and structural components that were supporting the building just a moment ago (with an area greater than that of a football field) will undoubtedly be found to be behaving in a manner very much like air (below left). It will take very careful calculation to tell the fall times apart during this free fall period of the ongoing progressive structural failure (below right)"....[/center]
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Not only is it
improbable, it's
impossible that the lower asymmetrically damaged part of the building could have naturally progressively collapsed in a way that resulted in the upper part of the building actually
accelerating as it descended symmetrically straight down through itself, through the path of greatest resistance (below right), and that driven on
solely by gravity, it actually
continued to accelerate so nearly to gravitational acceleration (below left) as to require
very careful calculation for any difference between the two to be detected....
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For the 2.25 seconds (eight stories, approximately 105 feet) that we
know the upper part of the building
literally fell at gravitational acceleration it
cannot have been using
any of it's potential energy to crush the building contents, columns and other structural components beneath it and undergo free fall
at the same time....
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[center]Control on the right, details....
http://picasion.com/pic76/ef2992a1bed34a1ad9d2e8f520c5ad7e.gif[/center]
Some
other force powerful enough to quickly remove
all support from beneath the upper part of the building as it descended
must be introduced to explain the observed rate of descent during the 2.25 second period of gravitational acceleration.
For the 2.25 seconds that the building
iliterally fell at gravitational acceleration, no
other force powerful enough to quickly remove
all support from beneath the upper part of the building was seen to be introduced from
outside the building, and no
other force powerful enough to quickly remove
all support from beneath the upper part of the building is known to have existed
inside the building as an element or normal function of it's infrastructure.
For a load supported by a column to descend at gravitational acceleration, all support
must be quickly removed, there's
absolutely no other way. It
must be knocked out, pulled out, blown out, vaporized, etc.
Since no eight story tall boulders were seen rumbling through Manhatten that day that could have quickly
knocked out all support....
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[center]Control on the right, details....
http://picasion.com/pic76/ef2992a1bed34a1a...8f520c5ad7e.gif[/center]
....and no suspicious looking Frenchmen were spotted rigging for verinage (another form of controlled demolition) the night before that could have quickly
pulled out the support....
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[center]Control on the right, details....
http://picasion.com/pic76/ef2992a1bed34a1a...8f520c5ad7e.gif][/center]
....and no bombs or rockets were seen to be dropped on/fired at it that could have quickly
blown out all support....
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[center]Control on the right, details....
http://picasion.com/pic76/ef2992a1bed34a1a...8f520c5ad7e.gif[/center]
....and no giant laser beams or other secret weapons were being tested in the area that could have quickly
vaporized all support....
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[center]Control on the right, details....
http://picasion.com/pic76/ef2992a1bed34a1a...8f520c5ad7e.gif[/center]
....and no
other force capable of quickly removing all support from beneath the upper part of the building existed in the building as a normal function of it's infrastructure, it
naturally follows that whatever the
other force was that
must be introduced to explain the observed 2.25 seconds of descent at gravitional acceleration, it
must have been introduced some time
before the event, and unless someone can show how the
other force that
must be introduced either
during or just
before the collapse of the building was introduced from
outside the building, or that it was already existing
inside the building as a normal function of it's infrastructure, the process of elimination really leaves
only one possible explanation for the building's behaviour.
Some energetic material powerful enough to quickly remove all support from beneath the upper part of the building during the 2.25 second period of gravitational acceleration
must have been physically transported
inside the building some time
before the event, it
had to be
brought in.
The explosion model (below) is the
only one....
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....that can
realistically match and empirically be
expected to create the conditions (below) that we
know must have existed....
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....beneath the
literally falling visible upper part of the building (below) during its observed largely symmetrical descent at gravitational acceleration for approximately 105 feet in 2.25 seconds....
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The undisputed (both the NIST and independent researchers alike agree) confirmed observation of a significant period of gravitational acceleration....
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....means an explosion, or a number of explosions,
must have occurred that was powerful enough to quickly remove
all support from beneath the upper part of the building (below right), either all at once or incrementally in advance of its descent, permitting it to descend at gravitational acceleration for the observed period and under the conditions required (below left) for free fall to occur....
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The building was brought down by explosives.